1. Field of the Invention
The invention generally relates to an apparatus and method of making a sensor design for a capacitive sensor, and more particularly to an indium tin oxide (ITO) sensor design for a liquid crystal display (LCD).
2. Discussion of the Related Art
Currently touch capacitive sensors are used widely for a number of different touch screens, e.g., continuous capacitive sensors and discontinuous capacitive sensors. FIG. 1A illustrates a top view of a related art sensor assembly. FIG. 1B illustrates a cross-sectional view of the sensor assembly in FIG. 1A.
Referring to FIGS. 1A-1B, the sensor assembly is generally depicted as reference number 100. The sensor assembly 100 includes a receiver line 102, a transmitter line 104 and an insulator 106 arranged between the receiver line 102 and the transmitter line 104. The receiver line 102 and the transmitter line 104 are arranged in a diamond pattern.
FIG. 2 illustrates a cross-sectional view of a related art sensor of FIG. 1 in a LCD display apparatus. Referring to FIG. 2, the LCD display apparatus is generally depicted as reference number 200. The LCD display apparatus includes a LCD 202 and a sensor assembly 100, with LCD 202 being located underneath the sensor assembly 100. An air gap between the LCD 202 and sensor assembly may be about 0.35 mm, thereby creating a capacitance between the receiver line 102 and the transmitter line 104, e.g., about 2 pF or bigger. In operation the voltage of the VCOM plane (not shown) may change in a square wave manner as shown in FIG. 2 and may have a magnitude of about 7Vp-p. FIG. 4 illustrates an electric field simulation of noise generated in operation of related art device of FIG. 2.
Referring to FIGS. 3 and 4, it shown that the electric field from the VCOM plane (not shown) may go directly to the receiver line 102. More specifically, when the VCOM voltage changes it injects a charge into the receiver line 102 (noise), which leads to measurement error. Therefore, the related art design exposes the receiving line to LCD noise.
Accordingly, there is a need to overcome the problems with the related art described above.